Armor piercing shell



Oct. 24, 1967 DUFOUR 3,348,485

ARMOR PIERCING SHELL Filed Oct. 5, 1965 United States Patent 47, 2 Claims. (Cl. 102-52) ABSTRACT OF THE DISCLOSURE The core of the shell according to this invention which is surronded by an envelope has a cup-shaped front part, the edge of this cup-shaped part constituting the only portion of the core projecting toward the front, the angle made, in a radial plane of the shell, between the tangent at said edge to an axial section of the outer surface of said core and a parallel to the shell axis ranging from 25 to 35 and the angle made, also in said radial plane, between said tangent and the tangent to said cup at said edge being substantially equal to 90.

The present invention relates to armor piercing shells comprising a core of hard material and an envelope of a light material the diameter of which is greater than that of the core. The hard material may be a sintered metal or alloy. The light material must have a density substantially lower than that of steel and may be an aluminum alloy, or possibly a plastic material.

The object of the present invention is to improve the capacity of penetration of such shells into targets the surface of which is not perpendicular to the shell trajectory.

The shells according to the present invention are characterized by the fact that the front end of their core is in the form of a cup the edge of which constitutes the most forwardly projecting portion of said core. The diameter of this edge is preferably at most equal to one half of the diameter of the main cylindrical portion of the core.

The core may be fixed to the envelope in the axial direction by glueing, in particular by means of an adhesive material consisting of a solution of an etboxyline or a similar resin.

The invention is also concerned with a method of manufacturing such cores when they are made of a sintered metal or alloy, the object being to reduce the risks of breaking of the envelope bottom.

The method according to the present invention is characterized by the fact of making use of a sintering mold having a slightly convex face in the portion thereof corresponding to the rear face of the core to be sintered, whereby this rear face of this core is normally slightly concave, or possibly accidentally flat, but is never convex.

A preferred embodiment of the present invention will be hereinafter described with reference to the appended drawings, given merely by way of example, and in which:

FIG. 1 is an axial sectional view of an armor piercing shell made according to the present invention;

FIG. 2 shows, partly and in sectional view, the mold to be used for sintering the core of said shell; and

FIG. 3 is a diagram illustrating the advantages of the shell according to the present invention.

It will be supposed that the invention is applied to the case of a shell of small caliber, for instance twenty millimeters.

This shell includes a core 1 made of a hard material, in particular of a sintered metal or alloy, such as tungsten carbide, and an envelope of a light material, in particular of an aluminum alloy. Advantageously, this envelope comprises an ogive 2 and a hollow body 3, assembled together in any suitable manner, for instance by screwing or by stamping.

In projectiles of this kind, the core is generally in the form of a cylinder terminating, at the front end thereof, in a central point. This shape would be the best if the projectile were to pierce only targets having their surfaces substantially perpendicular to the shell trajectory. As a matter of fact, the target surfaces nearly aways make an angle different from with this trajectory, and as this angle becomes smaller and smaller, it is found that the shells, instead of piercing the target, ricochet thereon in a proportion greater and greater.

In order to remove this drawback, according to the present invention, the front end of core 1 is given the shape of a cup 4, the edge 5 of this cup constituting the most forwardly projecting portion of the core. This edge is preferably slightly rounded off.

Advantageously, the diameter d of edge 5 is at most equal to one half of the diameter D of the usual cylindrical portion of core 1, so that the core may have a sufficient piercing capacity. The lower limit of diameter d is in accordance with the conditions of mechanical resistance to shocks, since the front portion of the core must not, as far as possible, break or separate from the body of the core when impinging upon an obstacle.

In order to define the shape of the cup 4 formed at the front of core 1, it is of interest to give suitable values, on the one hand, to the angle A made, in a radial plane, by the tangent T at said edge 5 to the axial section of the outer surface of the core with a parallel to the axis of the core and, on the other hand, to the angle B made, also in said radial plane, by this tangent T with the tan- 30 and that the best close to 90".

For an armor piercing shell of twenty millimeters caliber, the following dimensions have been satisfactory:

the length of the core being about 43 mm.

The shell may further comprise, in the usual manner, a pyrotechnic composition 6 (for instance an incendiary or tracer composition) housed in a cavity provided at chamber 7 limited inside envelope 2, 3 by the front portion of core 1.

Finally, the envelope body 3 is fitted with a rotating band 8, for instance of copper, sintered iron, soft steel, having an external diameter greater than that of envelope body 3.

Core 1 may be fixed to the envelope, and in particular to the body 3 thereof, by glueing, in particular by means of an adhesive substance consisting of a solution of an ethoxyline or similar resin, for instance of the kind of that designated by the trademark Araldite. The glueing area has been shown at 9 on FIG. 1.

This permits both of ensuring a rigid abutment between the elements 2 and 3 of the envelope and of having core 1 applied against the bottom 10 of body 3 despite the tolerances existing for the longitudinal dimensions of core 1, ogive 2 and envelope body 3.

As a matter of fact, glueing on the body of envelope 3 permits of avoiding the holding means generally provided on ogive 2 to prevent core 1 from moving toward the front of the projectile during handling.

When core 1 is made of a sintered metal or alloy, it is advantageous to make use of a sintering mold 11 (see FIG. 2) the bottom 12 of which is slightly concave in the portion thereof corresponding to the rear face of the core to be sintered. Thus the rear face 13 of the sintered core is normally slightly concave or may be accidentally fiat, but it is never convex. As a matter of fact, it has been found that, with the usual molds having a flat face in the portion thereof corresponding to the rear face of the core, there is obtained a certain amount of cores having a slightly convex rear face, which subsequently caused breaking of the bottom of envelope body 3.

On the contrary, according to the present invention, when the rear face 13 of the core undergoes deformations when it is cooled after sintering, this face risks at most being fiat but is never convex. Thus, either an annular or a flat contact of the core with the bottom of envelope 3 is obtained and there is no risk of breaking.

Finally, in order to facilitate the sintering of the front portion of the core, it is of interest to substitute, for the conventional ogive shape, a combination of two frustoconical surfaces 14 and 15 inscribed in an ogive.

The armor piercing shell according to the present invention works as indicated by FIG. 3. This figure shows, in abscissas, the angle C made by the trajectory of the shell with the surface struck by said shell and, in ordinates, the thickness e of an armored wall of constant quality. Curve a in dotted lines shows the capacity of penetration of a conventional shell as a function of angle C. Curve b in dot-and-dash lines shows this capacity for a shell having a core according to the present invention. The capacity of penetration is slightly smaller for a shell according to the present invention for values of angle C close to 90. But on the contrary the shell according to the present invention shows a great improvement for values of angle C lower than 60". Besides, curves a and b do not illustrate the frequency of misfires due to ricochets of the projectile on the armor and it should be pointed out that the proportion of these misfires is substantially higher in the case of curve a (conventional shell) than in that of curve b (shell according to the invention). This reduction of the ricochets may be explained by the fact that, according to the invention, the point where the target is struck by the edge 5 of cup 4, due to the fact that it is offset with respect to the longitudinal axis of the core, creates a torque tending to make the shell perpendicular to the target, which is of course favorable to the piercing of said target. If a portion of the core other than the edge 5 of its cup 4 were located more 5 at the front than said edge 5, the results would be much less favorable because this portion would eliminate the above mentioned torque.

In a general manner while the above description discloses what is deemed to be a practical and eflicient em- 10 bodiment of the present invention, said invention is not limited thereto as there might be changes made in the arrangement, disposition and form of the parts without departing from the principle of the invention as comprehended within the scope of the appended claims.

What I claim is:

1. An armor piercing shell which comprises, in combination, a core of a hard material and, about said core, an envelope of a light material of a diameter greater than that of said core, wherein the front part of said core is in the form of a cup the edge of which constitutes the most forwardly projecting portion of said core and wherein the angle made, in a radial plane of the shell, between the tangent at said edge to an axial section of the outer surface of said core and a parallel to the shell axis ranges from 25 to 35 and the angle made, also in said radial plane, between said tangent and the tangent to said cup at said edge is substantially equal to 90 2. An armor piercing shell according to claim 1 wherein the diameter of said edge is at most equal to one half of the diameter of the main cylindrical portion of the core.

References Cited UNITED STATES PATENTS 572,400 12/ 1896 Bakewell 102-56 1,419,361 6/1922 Cox 10252 2,276,100 3/ 1942 Snelling 102-56 2,342,006 2/ 1944 Moore 102--52 2,364,643 12/ 1944 Moore et a1 102-56 0 2,922,366 1/ 1960 Lyon 102--52 3,096,715 7/1963 Dufour 102-52 FOREIGN PATENTS 476,927 9/1915 France.

BENJAMIN A. BORCHELT, Primary Examiner.

SAMUEL FEINBERG, Examiner. W. KUJAWA, Assistant Exiaminer. 

1. AN ARMOR PIERCING SHELL WHICH COMPRISES, IN COMBINATION, A CORE OF A HARD MATERIAL AND, ABOUT SAID CORE, AN ENVELOPE OF A LIGHT MATERIAL OF A DIAMETER GREATER THAN THAT OF SAID CORE, WHEREIN THE FRONT PART OF SAID CORE IS IN THE FORM OF A CUP THE EDGE OF WHICH CONSTITUTES THE MOST FORWARDLY PROJECTING PORTION OF SAID CORE AND WHEREIN THE ANGLE MADE, IN A RADIAL PLANE OF THE SHELL, BETWEEN THE TANGENT AT SAID EDGE TO AN AXIAL SECTION OF THE OUTER SURFACE OF SAID CORE AND A PARALLEL TO THE SHELL AXIS RANGES FROM 25* TO 35* AND THE ANGLE MADE, ALSO IN SAID RADIAL PLANE, BETWEEN SAID TANGENT AND THE TANGENT TO SAID CUP AT SAID EDGE IS SUBSTANTIALLY EQUAL TO 90*. 